From the home screen of the Frontpoint App locate the Lights section. There you will see a listing for each light you have and the buttons to control them.
Tap on the yellow light icon to turn the light on.
Tap on the black light icon to turn the light off.
Use the slider bar to set the light to a specific brightness.
If you click on the right arrow icon you can go to the lights page where there will be an option to turn on/off all of the lights at once.